What human foresight could do to prevent democracy from regaining the ascendency, Sylla had thus accomplished. He had destroyed the opposition; he had reorganized the constitution on the most strictly conservative lines. He had built the fortress, as he said; it was now the Senate's part to provide a garrison; and here it was, as Caesar said afterward, that Sylla had made his great mistake. His arrangements were ingenious, and many of them excellent; but the narrower the body to whose care the government was entrusted, the more important became the question of the composition of this body. The theory of election implied that they would be the best that the Republic possessed; but Sylla must have been himself conscious that fact and theory might be very far from corresponding. The key of the situation was the army. As before, no troops were to be maintained in Italy; but beyond the frontiers the provinces were held by military force, and the only power which could rule the Empire was the power which the army would obey. It was not for the Senate's sake that Sylla's troops had followed him from Greece. It was from their personal devotion to himself. What charm was there in this new constructed aristocratic oligarchy, that distant legions should defer to it--more than Sylla's legions had deferred to orders from Cinna and Carbo? Symptoms of the danger from this quarter were already growing even under the Dictator's own eyes, and at the height of his authority. Sertorius had escaped the proscription. After wandering in Africa he made his way into Spain, where, by his genius as a statesman and a soldier, he rose into a position to defy the Senate and assert his independence. He organized the peninsula after the Roman model; he raised armies, and defeated commander after commander who was sent to reduce him. He revived in the Spaniards a national enthusiasm for freedom. The Roman legionaries had their own opinions, and those whose friends Sylla had murdered preferred Sertorius and liberty to Rome and an aristocratic Senate. Unconquerable by honorable means, Sertorius was poisoned at last. But his singular history suggests a doubt whether, if the Syllan constitution had survived, other Sertoriuses might not have sprung up in every province, and the Empire of Rome have gone to pieces like the Macedonian. The one condition of the continuance of the Roman dominion was the existence of a central authority which the army as a profession could respect, and the traditionary reverence which attached to the Roman Senate would scarcely have secured their disinterested attachment to five hundred elderly rich men who had bought their way into pre-eminence.